Tube heater



Patented June 28, 1938 UNITED STATES" PATENT osFica v TUBE HEATERGodfrey W. Larson, Kansas City, Mo., assignor to Standard Oil Company,Chicago, 111., a cor poration of Indiana I Application December so,1933, Serial No. 704,803

12' Claims. (c1. 122-356) This invention relates to improvements in tubeheaters, particularly tube heaters for use in the cracking and/ornon-cracking distillation of petroleum oils. More particularly itrelates to improvements in the arrangement of tubes, especially floortubes within avtube heater having a radiant section and a convectionsection.

It is known to use one or more banks of tubes located at or near thefloor of the so-called radiant section of a tube heater and it is known.that-this practice has many advantages, one of the most important ofwhich is increased thermal efficiency. It is anobject of myinvention toincrease this thermal efflciency by an improved arrangement of the floortubes. Other objects of my invention are to reduce convective action inthe radiant section, provide streamline flow and avoidlocal overheating.Further and more detailed objects will become apparent as thedescription proceeds.

I have illustrated my invention in the drawing in which:

Figure 1 is a schematic cross-sectional eleva- 4 tion of a tube heaterembodying my invention;

"and,

Figure 2 is a schematic cross-sectional elevation of a tube heaterembodying a modified form of I my invention. 1

Referring-now more particularly to the drawving, II is the radiantsection and I2 the convectionsection of a tube heater comprising sidewalls I3 and I4, roof l5 and floor l6. A suitable,

fuel such as gas, oil or powdered coal is intro- -duced. through one orpreferably a series of ports |'I, located near the bottom of side walll3, by

means of burners I8 controlled by valves is.

The flame from burners 8 proceeds generally upward and across radiantsection II as indicated by lines 20 and the combustion gases pass overbridge wall 2|, down through convection section 2 and out at 22 to astack not shown.

The fconventional floor tube practice in the past has been to-placethese tubes in a horizontal row along the conventionr l, horizontalfloor I6 (Figure l) in radiant section II.

thermal efllciency since those floor tubes nearest bridge wall 2| aremuch further from flames 20 do those floor tubes nearest wall; [3.particularly important in large heaters since the than those floor tubesnearest wall I3. In other words, those flo'or tubes nearest bridge wall2| in the conventional arrangement have a much smaller projected area asviewed from the hot spot? or center of heat of radiant section II thanThisis tween the various floor tubes 23.

I flnd, however, .that this results'in poor heat pick-up or stack effectof the hot gases in the radiant section pulls" the flames upwardresulting in a higher hot spot and a lower heat pick-up in the floortubes nearest the bridge wall.

I have remedied this defect by inclining-the 5 plane of the floor tubes23 upward towards bridge wall 2| insuch a manner that the axes of thevarious 'floor tubes 23 are substantially equidistant from flames 20 orthe edge thereof. In Figure lthis is done by inclining the plane 1 ofthe floor tubes, the imaginary line ,2! connecting floor tubes 23 andperpendicular to them being a straight line. In Figure 2 the imaginaryline 24 conforms still more closely to the shape of flame 20, the shapeof line 24 in this case the flame also serves to protect the bridge wall2 tubes.

Alternatively, a cheaper construction can be'used consisting of astepped-construction ZSadjacent .to bridge wall 2| as shown in Figure 1or throughoutthe whole length of floor l6.

Under certain circumstances, as for example,

when powdered coal is employed as fuel it may be advantageous to buildthe floor entirely in a horizontal plane or alternatively to build thefloor to function as an ash pit or sump. Any

of these modifications may be employed without departing from the spiritof my inventions.

It is to be understood that many different routings' of oil or otherfluid to be heated through a tube heater embodying my invention can suitably be useddepending on the results desired to 40 be accomplished. Inthe drawing the fluid to be heated enters-at 26 and passes back andforth through the lower bank of convection tubes A, the cold fluidthereby picking up the last avail-- able heat from the hot combustiongases leaving the tube heater. The partially heated fluid passes out at21 and thence to bank B composed of floor tubes 23. After passing backand forth through floor tubes 23 the fluid passes to bank C composed oftubes mountedadjacent to bridge wall 2| ,and wall l3. The tubes in bank0 are preferably arranged so that the fluid passes around radiationspace H first through a tube adjacent wall 2| and'then through a tubeadjacent wall 13. vFro n bank C, the fluid under- H and avoids localoverheating which 9 going heating passes through line 28 to roof tubebank D, shown as a double bank. After passing back and forth through thetubes of bank D the fluid passes through line 29 to upper convectionsection bank E and thence out at 30.

Conventional headers are used to connect the various tubes.

Alternatively the fluid to be heated could be passed through floor tubebank B first, thereby protecting these tubes against overheating orthrough floor tube bank B last, thereby heating the fluid to a highertemperature. be omitted and many other modifications are possible.

A similar but generally lesser advantage can be obtained by arrangingthe roof tubes or other tubes located above the flames to conform to theshape of the flames in the same manner as shown for the floor tubes.

It will be noted that the floor tubes are ar-- ranged transverse to thedirection of travel of the flames. This is 'highly preferable toarranging them parallel to the flames since in an ordinary radiantsection the tubes can thus be made to conform to the shape of the flameswithout using.

curved tubes and the tubes are made readily accessible by the use ofconventional headers.

While I have shown and described my invention in connection with certainspecific embodiments thereof, I do not mean to be limited thereby butonly by the scope of the appended claims.

I claim: 1. A tube heater comprising a radiant section, a convectionsection, a bridge wall disposed between said radiant section and saidconvection section, at least one fuel burner entering said radiantsection nearthe bottom thereof and opposite said bridge wall, the flamesfrom said at least one burner passing generally upward and across saidradiant section towards the top of said bridge wall, and a row ofheating tubes disposed generally below said flames and tilting upwardstoward said bridge wall, the floor of said radiant section beingdisposed immediately below and substantially parallel to said row ofheating tubes.

2. A tube heater comprising a radiant section, a

convection section, a bridge wall disposed between said radiant sectionand said convection section, at least one fuel burner entering saidradiant section near the bottom thereof and opposite said bridge wall,the flames from said at least one burner passing generally upward andacross said radiant section towards the top of said bridge wall, and aplurality of heating tubes arranged approximately transversely to thedirection of flame travel in a bank disposed generally below said flamesand tilting upwards towards said bridge wall.

3. A tube heater according to claim 2 in which the floor of said radiantsection is stepped upward adjacent to said bridge wall to levelsimmediately below the corresponding levels -of said heating tubes.

4. A tube heater comprising a radiant section, a convection section, abridge wall disposed between said radiant section and said convectionsection, at least one fuel burner entering said radiant section near thebottom thereof and opposite said bridge wall, the flames from said atleast one burner passing generally upward and across said radiantsection towards the top of said bridge wall, and a plurality of heatingtubes'arranged approximately transversely to the direction of flametravel in a bank disposed generally below Bank C can said flames andconforming generally to the shape of said flames.

5. A tube heater according to claim 4 in which 6. A tube heatercomprising a radiant section, a convection section, a bridge walldisposed between said radiant section and said convection section, atleast one fuel burner entering said radiant section near the bottomthereof and opposite said bridge wall, the flames from said at least oneburner passing generally upward and across said radiant section towardsthe top of said bridge wall, and a plurality of heating tubes arrangedapproximately transversely .to the direction of flame travel in a bankdisposed generally below said flames and lying in a substantiallyhyperbolic surface conforming generally to the shape of said flames.

7 s A tube heater comprising a radiant section, a convection section, abridge wall disposed between said radiant section and said convectionsection, at least one fuel burner entering said radiant section near thebottom thereof and opposite said bridge wall, the flames from said atleast one burner passing generally upward and across said radiantsection towards the top of said bridge wall, and a plurality of heatingtubes disposed generally below said flames with their axes approximatelyequidistant from said flames and approximately transverse to thedirection of flame travel.

8. A tube heater of the open flame type comprising a burner andheatingtubes disposed transversely to the direction of flame travel andarranged in a bank conforming approximately to the shape of theunderside of the flame, said bank rising in a direction away from saidburner from a level immediately below the level of said burner to alevel above the level of said burner,

9. A tube heater comprising a radiant section, a convection section, abridge wall disposed between said radiant section and said convectionsection, at least one fuel burner for said radiant section near thebottom thereof and opposite said bridge wall, the gases from said atleast one burner passing generally upward and across said radiantsection towards the top of said bridge wall, and a row of heating tubesdisposed generally below said gases and tilting upwards toward saidbridge wall, the floor of said radiant section being disposedimmediately below and substantially parallel to said row of heatingtubes.

rection of gas travel in a bank disposed generally .leastonebumerpassing generally upward and erally upward and across said radiantsection,.

across said radiant section towards the top of said bridge wall, and aplurality of heating tubes disposed generally below said gases withtheir axes approximately equidistant from said gases and approximatelytransverse to the direction of gas. travel.

l2. Aitube heater comprising a radiant section, a convection section, atleast one fuel burner for said radiant section near the bottom thereof,the gases from said at least one burner passing genand a plurality ofheating tubes disposed in a row generally below said gases with theiraxes approximately equidistant from said gases and approximatelytransverse to the direction of gas travel, the floor of said radiantsection being disposed immediately below and substantially parallel tosaid row of heating tubes. v

GODFREY W. LARSON. 10

